The N-(hydroxy and C.sub.4 - C.sub.24 alkyl-substituted benzyl) alkylene polyamines of the class H.sub.2 N--(R--NH).sub.n H, wherein R, is a C.sub.2 to C.sub.6 alkylene hydrocarbon radical and n is an integer of from 1 up to 10 have been long known. Such N-substituted alkylene polyamines are derived from the condensation of a C.sub.4 - C.sub.24 alkylphenol, a source of formaldehyde and an alkylene polyamine of the above formula. Those skilled in the art of formulating crankcase lubricant compositions know that the above long known N-substituted alkylene polyamines impart little or no significant detergency function to oils use to lubricate the internal moving parts of internal combustion engines in use since the advent in 1960 of increasingly severe restrictions on gas and vapor emission from the engines crankcase.
Such detergency deficient N-(hydroxy and C.sub.4 - C.sub.24 alkyl-substituted benzyl) alkylene polyamines were improved with respect to detergency by their modification, according to U.S. Pat. No. 3,458,495, with a phosphosulfurized 500 to 200,000 (Staudinger) molecular weight hydrocarbon which could be a terpene, a heavy petroleum fraction or a polymer of a C.sub.2 to C.sub.6 olefin. The improved addition agent of said patent is obtained by reacting at a temperature of from 93.degree. up to 232.degree. C one molar proportion of such phosphosulfurized hydrocarbon with from 0.5 up to 4 molar proportions of the N-(hydroxy and C.sub.4 - C.sub.24 alkyl-substituted benzyl) alkylene polyamines.
The above phosphosulfurized modified N-(hydroxy and C.sub.4 - C.sub.24 alkyl-substituted benzyl) alkylene polyamines are recognized as representing prior art knowledge closest to the present inventive addition agents. Such close prior addition agents are, as will be later demonstrated, deficient with respect to detergency-dispersancy requirements of present day internal combustion engines which have been required to have a substantially closed system coupling the vapor space of the crankcase and combustion chambers of the engines so that there is no venting of the crankcase to the atmosphere. Such a closed, coupled system by recycle of combustion products passing by the piston rings to the crankcase and lubricant oil decomposition products cause the formation of oil-insoluble sludges which are more difficult to disperse in the lubricating oil. Also the closed, coupled system materially enhances partial oxidation of petroleum derived lubricating oils causing them to have a four-fold increase in viscosity in a relatively short time, about 20-35 hours of engine operation.
Although the closest prior art addition agents of U.S. Pat. No. 3,458,495 were suitable detergents at the time of their discovery and disclosure in 1965, it is understandable that they are now detergency and dispersancy deficient more than ten years later because of the above-mentioned more severe service imposed by the required use of the closed, coupled system between the crankcase and combustion portions of the internal combustion engines.
Another drawback of said closest prior art addition agents comes from the use of phosphosulfurized hydrocarbons of a molecular weight above 2800 which corresponds to a carbon content in the molecule of above 200. Such hydrocarbons of molecular weight above 2800, and especially the olefin polymers, vary from extremely viscous liquids to semisolids at ambient temperature. For example, at a molecular weight of about 3000 such hydrocarbons will have a viscosity above 200,000 centistokes at 37.5.degree. C and above 6000 at 98.5.degree. C. After conversion of such 2800 and high molecular weight hydrocarbons with a phosphorus sulfide to the phosphosulfurized derivative, the phosphosulfurized hydrocarbon product not only retains the exceptionally high viscosity of its hydrocarbon precursor but also has a higher viscosity. The use of phosphosulfurized hydrocarbons of greater than 200 carbon content to modify the N-(hydroxy and alkyl-substituted benzyl) alkylene polyamines leads to addition agents which at conventional use in lubricating oil, from 0.1 up to 10 weight percent of the oil, would provide a lubricant oil composition of undesirably high viscosity at temperatures from ambient up to engine operating temperatures.
For the beneficial use of the present inventive addition agents, it is not necessary to use a phosphosulfurized hydrocarbon derived from a hydrocarbon of molecular weight above 2800. Rather such phosphosulfurized hydrocarbon reactant is one which has been obtained by the reaction of a phosphorus sulfide, preferably phosphorus pentasulfide, with an olefin polymer of number average molecular weight (M.sub.n) in the range of from 500 up to 2600, preferably from 700 up to 2240. Such olefin polymers have a number average carbon (C.sub.n) content of from about 35 up to about 186, preferably from 50 to about 160 C.sub.n.
However, the present inventive addition agent differs more than in the foregoing basis for selection of the phosphosulfurized hydrocarbon reactant. While such selection provides part of the novelty for the present inventive addition agent, the remaining portion of the novelty comes from the selection of the N-(hydroxy and alkyl-substituted benzyl) alkylene polyamine reactant. For the selection of such N-substituted alkylene polyamines, it is the selection of its alkyl-substituted phenol precursor that is believed to be of importance with respect to the above-mentioned remaining novelty. For such N-substituted alkylene polyamine reactant the alkylphenol reactant of importance has an alkyl-substituent derived from an olefin polymer having a carbon content of from about 50 up to about 160 which corresponds to a 700 up to 2240 M.sub.n. The upper limit on the size of such olefin polymer derived alkyl-substituted is also related to the viscosity characteristics of the olefin polymer which is used to alkylate phenol to obtain the alkylphenol precursor of the N-substituted alkylene polyamine portion of the present inventive addition agent.
The same viscosity-molecular weight correlation discussed with respect to the phosphosulfurized hydrocarbon reactant are applicable to the correlations between viscosity-molecular weight of the olefin polymer which also carry through to both the alkylphenol precursor and the N-substituted alkylene polyamine. But such selection of alkylphenol precursor of the N-substituted alkylene polyamine is of further importance to the unexpected dispersancy function of the present inventive addition agent.
It is the combination of the technical effects of the selected phosphosulfurized 500-2600 M.sub.n hydrocarbon and the selected N-(hydroxy and alkyl-substituted benzyl) alkylene polyamine reactants and the proportions of such reactants later given which provide the novelty for the present inventive addition agent which imparts anti-oxidant, detergency and unexpectedly superior dispersancy functions to lubricant oil fractions of petroleum.
The closest prior art phosphosulfurized hydrocarbon modified N-(hydroxy and alkyl-substituted benzyl) alkylene polyamines are disclosed as being produced in three steps. The phosphosulfurized hydrocarbon reactant is separately prepared The second step comprises the condensation of the C.sub.4 - C.sub.24 alkylphenol, a source of formaldehyde (e.g. formalin or paraformaldehyde) and alkylene polyamine. In the last step one molar proportion of the phosphosulfurized hydrocarbon is reacted at a temperature of from 93.degree. up to 232.degree. C with from 0.5 up to 4 molar proportions of the N-(hydroxy and C.sub.4 - C.sub.24 alkyl-substituted benzyl) alkylene polyamine condensation product of the second step. While products analagous to the present inventive addition agent can be produced by the same three reaction steps, the present inventive addition agent is preferably produced by only the following two reaction steps. The phosphosulfurized olefin polymer is separately prepared and then combined with the C.sub.50 - C.sub.160 alkylphenol and the alkylene polyamine followed by addition of a source of formaldehyde to the three combined reactants to complete the production of the present inventive addition agent for lubricant oil fraction of petroleum.
Such preferred two step reaction is, from the following considerations, novel in view of the three step prior process for producing the closest prior art addition agents. It is known that the phosphosulfurized olefin polymer is acidic in nature and will readily react with an alkylene polyamine. Such reaction does in fact occur in the second step of the preferred two step reaction. the character and nature of such reaction is not known and not important to the present invention except that the product of such reaction does have at least one hydrogen on a nitrogen atom in the reaction producct to undergo a condensation reaction with formaldehyde and the alkylphenol and split out water as a by-product.
Because one molar proportion of the phosphosulfurized olefin polymer hydrocarbon can be reacted with less than, more than and equal molar proportions of each of the C.sub.50 - C.sub.160 alkylphenol alkylene polyamine and formaldehyde, the present inventive addition agent resulting therefrom can not be characterized in the normal manner, i.e. by structural formula. Moreover, both the phosphosulfurized hydrocarbon and alkylphenol reactants are derived from olefin polymers which even when designated by a single M.sub.n, e.g. 900 M.sub.n, are not single molecular entities but rather are mixtures of higher and lower molecular weight species. This further prevents characterization of the present inventive addition agent in a normal manner for identifying organic chemical compounds.
The character and nature of the phosphosulfurized olefin polymer is further complex with respect to its phosphorus and sulfur linkages carrying through from the phosphorus sulfide reactant. There is definitely a quite stabile carbon-to-phosphorus linkage but there are both coordinate and polar linkages between the phosphorus and sulfur atoms. The preferred phosphosulfurized olefin polymer obtained from phosphorus pentasulfide can have carbon-to-sulfur, carbon-to-phosphorus, mono-and di-coordinate linkages between phosphorus and sulfur and polar linkages between phosphorus and sulfur as in the following structure from one mole of P.sub.2 S.sub.5 and two moles of olefin polymer: ##STR1## Such a complex molecule has many potential routes for reaction with an alkylene polyamine.
Because of the foregoing complexities associated with the preparation and formation of the present inventive addition agent, it can be only defined as a reaction product in terms of its reactants, their molar proportions, and reaction conditions.